Molten aluminum is cast or rolled into blank bodies such as slabs, sheets and tubular lengths. These are commonly referred to as ingots or billets. The blanks are then reworked to convert them into useful forms. The resulting products include such diverse items as food and beverage containers, electrical wire, and automotive parts.
The reworking operation, in general, involves compressing an aluminum blank against a mechanically strong, abrasion-resistant surface. This surface may be the interior of an extrusion die in the case of aluminum beverage cans. Aluminum wire is produced by drawing a cylindrical blank through a wire die. Aluminum sheet or foil results from drawing blank sheet through rollers.
Various ceramic materials, including Al.sub.2 O.sub.3, Si.sub.3 N.sub.4, SiC and WC, have heretofore been considered for use in aluminum reworking operations. Alumina, reinforced with SiC whiskers, has also been proposed. However, it proved to be unsatisfactory because of a problem with porosity. Tungsten carbide (WC) is currently used in commercial extrusion dies.
While the various ceramic materials are effective for the reworking purpose, they all leave room for improvement. In particular, they tend to produce a rough or matte surface on a reworked aluminum article. Also, some of the materials tend to wear relatively rapidly, thereby requiring frequent replacement.
It is then a basic purpose of the present invention to provide an improved material for use in fabricating articles from aluminum blanks. A further purpose is to provide a fabricated aluminum article with an improved surface finish.